Reciprocatory drive mechanisms



June 17, 1958 L. E. GILBERT RECIPROCATORY DRIVE MECHANISMS Filed Jiily 10, 1956 INVENTOR LLOYD G/L BEPT y 5 PA rE/Vr AGENT Unite States Patent Q RECIPROCATORY DRIVE MECHANISMS Lloyd E. Gilbert, San Jose, Calif. Application July 10, 1956, Serial No. 596,893

4 Claims. (CI. 74-54) The present invention relates to reciprocatory drive mechanisms andmore particularly to mechanisms for converting rotary motion to reciprocatory motion suitable for driving ore concentrating tables and the like.

Drive mechanisms of this type, perhaps more commonly designated as head-motion devices, are designed to impart a differential reciprocatory motion to the concentrator table or other structure whereby the ore or other material is advanced therealong. Such differential motion which provides a change in the table speed during the reciprocatory stroke must be carefully controlled to obtain maximum efficiency of ore concentration and obviously must be varied when ore of a different character is to be processed.

It is a primary object of the present invention to provide a drive mechanism of the general type referred to that is arranged to produce maximum effectiveness in use.

It is a feature of the invention to provide a drive mechanism whose differential motion and length of stroke can be readily varied during operation whereby the optimum effectiveness of operation can be empirically determined by direct visual inspection.

A further feature relates to the drive mechanism design that utilizes a minimum of moving parts wherefore ease of construction, simplicity of operation, and infrequency of repair are afforded. v

These and other objects and features of the invention will become more apparent from a perusal of the following description of the accompanying drawing wherein:

Fig. l is a vertical sectional view of a preferred embodiment of the invention, I

Fig. 2 is a transverse sectional view taken along line 2-2 of Fig. l, and

Fig. 3 is a fragmentary view taken substantiallyalong line 3-3 of Fig. 1.

Generally, a device embodying the present invention is of extremely simple construction including but two levers and a member adapted to transmit force therebetween. Motion imparted to one lever is transmitted through the intermediate member and the second lever to the concentrator table or other structure which is to be reciprocated. The arrangement is such that the position of the force-transmitting member can be adjusted so as ultimately to vary the length of the reciprocatory stroke and the differential motion of'the table during such stroke. The simple adjustment of the simple mechanism can be made during operation so that the results of such adjustment can be readily observed.

In the preferred embodiment shown in the drawing, the above-mentioned levers take the form of bell cranks, generally indicated at 10 and 12, which are appropriately mounted within a housing 14 in a manner to be more specifically described hereinafter. The housing 14 is of generally rectangular form, having, however, a small depending portion 14a at one end. Within this small depending portion 14a of the housing 14, lubricating oil is placed to a level indicated at L; and in more or less conventional fashion, this oil is caused to be splashed up with a motor (not shown).

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wardly in the housing during operation of the mechanism to effect lubrication of the moving parts. Preferably, the housing 14 has a removable top 16 to enable access to the interior for repairs or general servicing.

A drive shaft 18 extends transversely through the housing 14 in the dependent portion 14a thereof, being suitably supported for rotation in bearings 20, 22, supported at each side of the housing. A suitable pulley 24 is keyed to the shaft 18 exteriorly of the housing 14, and a V-belt 26 is mounted on the pulley to enable driving connection Within the housing 14, an eccentric 28 is secured on the shaft 18 in a position adjacent a semi-cylindrical bearing surface 30 formed integrally with one arm 32 of the first bell crank 10. This bell crank 10 is supported pivotally on a rod 34 that transversely bridges the housing 14, and is secured suitably in the side walls thereof. As shown, the aforementioned first arm 32, as well as the second arm 36 of the bell crank 10, each take the form of a flat plate which radiates from the hub portion 38 that surrounds the described pivot rod 34. To add rigidity to this bell crank structure, a bracing web 40 extends between the two arms 32, 36 thereof.

The second bell crank 12 is of generally similar structure including first and second arms 42,44 radiating from a hub portion 46 that surrounds a pivot rod 48 supported between the sides of the housing 14 and additionally having spaced webs 50 disposed between the two arms. This second bell crank 12 is disposed so that its first arm 42 extends generally in the direction of the first bell crank 10, and somewhat above the second arm 36 of such first bell crank, which, itself projects,generally, in the direction of the second bell crank 12.

Between such arms 36 and 42, the aforementioned force-transmitting member, generally indicated at 52, is disposed. As shown, this force-transmitting member 52 preferably takes the form of a pair of rollers 54, 56 arranged to engage the upper or outer surface of the second arm 36 of the first bell crank 10 and the inner or under surface of the first arm 42 of the second bell crank 12. As can best be visualized by reference to Fig. 2, the rollers 54, 56 lie between the spaced webs 50 of the second bell crank 12 so as to be retained against lateral displacement out of force-transmitting position. The rollers 54, 56 are mounted on a bar 58 that is connected for limited pivotal movement at its remote end to an actuating member 60. As shown in Fig. 1, such actuating member 60 takes the form of a threaded rod that extends through a threaded nut 62 attached to the housing 14 for connection at its extreme end to a suitable hand crank 64. When the hand crank 64 is turned, motion is transmitted through the threaded rod 60 and the bar 58 to displace the rollers 54, 56 in a direction longitudinally of the spaced arms 36, 42 of the two bell cranks 10 and 12. Motion in one direction brings the rollers 54, 56 closer to the pivot rod of one bell crank and farther from the pivot rod of the other; while motion of the rollers in the opposite direction will obviously have just the opposite effect.

At the remote end of the second arm 44 of the second bell crank 12, a pull rod 66 is pivotally attached so as to project through a suitable opening in the housing 14 for connection at its extreme end to aconcentrator table or other structure to be actuated and generally indicated at T. Exteriorly of the housing 14, a coil spring 68 surrounds the rod 66 and is compressed between a nut 7% on the pull rod 66 and a plate 72 that is adjustably attached to the housing 14 by adjustment screws 74. Turning of these adjustment screws 74 will vary the disposition of the plate 72 and thereby effect a variation in the spring compression. The force of such spring 68 urges the pull rod 66 to the left, as viewed in Fig. 1. Such force, in turn, tends to rotate the second bell crank 12 in a clockwise direction; and by transmission through the force-transmitting rollers 54, 56, urges the first bell crank H1 in a counterclockwise direction so that the bearing surface 34) on its first arm 32 is therefore urged against the described eccentric 23 on the drive shaft 18.

It will be seen from the foregoing that the coil spring 68 effects motion of the concentrator table. T to the left, as viewed in Fig. 1; while the eccentric 28, as it rises from its low to its high point, positively effects motion of the table T in the opposite direction, or to the right, as viewed in Fig. 1. A more detailed recitation of the exact character of the two motions can now be undertaken. If it is assumed that the eccentric 28 is at its high point, as shown in Fig. 1, and if the pulley 24 is rotating in a counterclockwise direction, as indicated by the arrow A in Fig. 1, the following action will take place. As the eccentric 28 moves in a counterclockwise direction with the pulley 24 and the drive shaft 18, the point of operative engagement of the eccentric 23 with the bearing structure 30 on the first bell crank 10 will decrease radially relative to the supporting drive shaft. The previously described spring action will move the pull rod 66 and bell cranks 10, 12 to maintain the bearing surface 30 of the first bell crank 10 against the inwardly displaced engagement point on the eccentric 28. The second bell crank 12 rotates in a clockwise direction while the first bell crank ltlrotates in a counterclockwise direction. The spaced rollers 54, 56 which transmit the motion between the bell cranks 10, 12 move downwardly, as viewed in Fig. 1, and will be displaced in an arc having the point of pivotal support for the rollers at the end of the adjusting rod 60 as its center. Therefore, the rollers in their downward arcuate path move closer to the pivot rod 34 of the first bell crank 10 and further from the pivot rod 48 of the second bell crank 12. A

change in leverage is thus encountered which effects a gradual deceleration of table motion for a given amount of drive shaft rotation until the low point on the eccentric 28 is reached.

As rotation of the eccentric 28 continues so that the point of engagement moves from the low point of the eccentric to the high point thereof, motion of the concentrator table T to the right, as viewed in Fig. 1, will be instigated; and since the converse of the above-described leverage exchange will be experienced, a gradual acceleration of table motion will be experienced until the high point of the eccentric is again reached. From the above description of the reciprocatory motion, it will be apparcut that an abrupt change of direction will be experienced at one end of the reciprocatory stroke while at the other end of such stroke, the change of direction will be quite gradual, such being precisely the action desired in the reciprocation of concentrating tables, screens, and other similar material separation devices.

It has been found that the precise reciprocatory stroke desired varies considerably in character for the separation of, for example, ores of variant character and constituents. When a certain ore is placed on a concentrator table actuated by the described mechanism, the separating function can be visually observed and by the simple turning of the hand crank 64, adjustment of the length of stroke and the differential motion can be made to enable a relatively quick and simple determination of the optimum character of reciprocatory stroke for the particular ore being processed.

It should be re-emphasized that this simple adjustment is made to optimize the processing in a mechanism which in and of itself is exceedingly simple, so that when needed replacements resultant from continued use must be made, the elements to be replaced and the cost of such-replacement is conseqently a minimum.

Various modifications and alterations can obviously be made without departing from the spirit of the present invention. As a consequence, the foregoing description of a preferred embodiment is to be considered as purely exemplary, and not in a limiting sense; the actual scope of the invention being indicated by the appended claims.

What is claimed is:

1. A reciprocatory drive mechanism for concentrator tables or the like which comprises a drive shaft, an eccentric mounted on said shaft for rotation therewith, a first bell crank mounted with one arm in operative engagement with said eccentric, a second bell crank with one arm disposed in spaced relation to the second arm of said first bell crank, a roller interposed between the spaced arms of said first and second bell cranks to transmit motion therebetween, a pull rod pivotally connected to the second arm of said second bell crank and adapted to transmit force to the concentrator table, and spring means urging said pull rod in one direction whereby force is transmitted through said pull rod and said cranks to urge said first bell crank into resilient engagement with said eccentric.

2. A reciprocatory drive mechanism according to claim 1 comprising means for adjusting the position of said motion transmitting roller relative to said bell cranks Whereby the leverage can be varied.

3. A reciprocatory drive mechanism for concentrator tables or the like which comprises a drive shaft, an eccentric mounted on said shaft for rotation therewith, a first bell crank pivotally mounted at a position such that one arm thereof is disposed in operative engagement with said eccentric, a second bell crank pivotally mounted at a position spaced from said first bell crank and having one arm projecting generally in the direction of said first bell crank, said first bell crank having a second arm projecting generally in the direction of said second bell crank, a roller interposed between the one arm of said second bell crank and the second arm of said first bell crank whereby motion can be transmitted therebetween, means for adjusting the position of said roller generally longitudinally of the bell crank arms whereby the leverage can be varied, and means for connecting a second arm of said second bell crank lever to the concentrator table.

4. A reciprocatory drive mechanism according to claim 3 wherein said roller is pivotally supported for displacement about a point adjacent the pivotal mounting position of said first bell crank.

References Cited in the file of this patent UNITED STATES PATENTS 2,080,665 Larsen May 18, 1937 2,693,708 Baer Nov. 9, 1954 FOREIGN PATENTS 518,990 Belgium Apr. 30, 1953 

